Sunday, March 10, 2013

One Becomes Two

Last November, I wrote about the initial thoughts we had to bring more capability to KL2R as a multi-two station.  After considerable research and planning, the efforts are coming to fruition in time for the spring contest season. 

Station Master

The Microham Station Master serves multiple functions. It ties together the Microkeyer II, bandpass filters, and SixPak antenna switch into a powerful, centrally-controlled system at each position.  The SM is far more than your standard band decoder.  You can build extremely sophisticated logic for switching, timing (to avoid hot switching), and miscellaneous device control.  To get started, you have to define bands and then associate these bands with specific antennas or antenna groups.  You can even build virtual rotators with fixed antennas on a tower, multiple Beverages, or a four-square, for example. 

A nice feature of the band definitions is the ability to limit transmissions to specific frequency ranges.  For instance, in a phone contest you might want to specify only the legal phone sub-bands.  In that way you avoid inadvertently chasing multipliers into the non-US segments.  The Station Master will simply not allow you to transmit there, thereby avoiding a possible OO card or FCC notice.

The two Station Masters control their respective sides of the SixPak 6x2 antenna switch at the tower along with bandpass filter arrays.  Two ports, A and B, with DB-25 connectors provide plenty of outputs for switch control.  Eventually we will add a second SixPak to the entrance to the shack to select antennas not going through the tower switch and thus consolidate all inputs to the radios to two coaxial lines.

The Bandpasser

At one position, the W3NQN bandpass filters are combined with an FM-6 switch from Array Solutions.  The SM selects the appropriate filter by applying +12 VDC to a specific pin on the switch's DB-9 connector.  The assembly is effective, of course, but bulky.  For the second position,  Hamation's AS-419 Bandpasser proved to be just the ticket.  It is a compact, book-sized unit with filters for all the non-WARC HF bands rated for 100 watts at 100% duty cycle.  Control can be asserted manually through front panel buttons, or remotely with a band decoder, in this case a Station Master.

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